Birth-Weight

Introduction

There are a variety of prenatal techniques for estimating approximate birth weight that are relevant for preterm, term and prolonged pregnancy. Ultrasound two- and three-dimensional scanning methods are the basis of most current techniques. There are also standard autopsy weight curves that have been developed from second and third trimester fetal and also neonatal autopsy.

At birth, infants are generally weighed as soon as possible and may also be monitored during the neonatal period.

Birth Weight Classifications

The primary causes of VLBW are premature birth (born <37 weeks gestation, and often <30 weeks) and intrauterine growth restriction (IUGR), usually due to problems with placenta, maternal health, or to birth defects. Many VLBW babies with IUGR are preterm and thus are both physically small and physiologically immature.

Human Birth Weight Classifications											no colour
Birth weight (grams)	less 500	500 – 999	1,000 – 1,499	1,500 – 1,999	2,000 – 2,499	2,500 – 2,999	3,000 – 3,499	3,500 – 3,999	4,000 – 4,499	4,500 – 4,999	5,000 or more
Classification	Extremely Low Birth Weight		Very Low Birth Weight	Low Birth Weight		Normal Birth Weight			High Birth Weight

Extremely Low Birth Weight

• Less than 500 grams (1 lb 1 oz or less)
• 500 – 999 grams (1 lb 2 oz – 2 lb 3 oz)

Very Low Birth Weight

• 1,000 – 1,499 grams (2 lb 4 oz – 3 lb 4 oz)

Low Birth Weight

• 1,500–1,999 grams (3 lb 5 oz – 4 lb 6 oz)
• 2,000–2,499 grams (4 lb 7 oz – 5 lb 8 oz)

Normal Birth Weight

• 2,500–2,999 grams (5 lb 9 oz – 6 lb 9 oz)
• 3,000–3,499 grams (6 lb 10 oz – 7 lb 11 oz)
• 3,500–3,999 grams (7 lb 12 oz – 8 lb 13 oz)

High Birth Weight

• 4,000–4,499 grams (8 lb 14 oz – 9 lb 14 oz)
• 4,500–4,999 grams (9 lb 15 oz – 11 lb 0 oz)
• 5,000 grams or more (11 lb 1 oz or more)
• see also * macrosomia

Birth Weight Table (no background)

Links: Ultrasound | Fetal Origins Hypothesis | Maternal Diabetes

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Cite this page: Hill, M.A. (2024, April 19) Embryology Birth-Weight. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Birth-Weight

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G